add numerical recipes library

lib/nr/cpp/recipes/tptest.cpp

@@ -0,0 +1,19 @@
+#include <cmath>
+#include "nr.h"
+using namespace std;
+
+void NR::tptest(Vec_I_DP &data1, Vec_I_DP &data2, DP &t, DP &prob)
+{
+	int j;
+	DP var1,var2,ave1,ave2,sd,df,cov=0.0;
+
+	int n=data1.size();
+	avevar(data1,ave1,var1);
+	avevar(data2,ave2,var2);
+	for (j=0;j<n;j++)
+		cov += (data1[j]-ave1)*(data2[j]-ave2);
+	cov /= df=n-1;
+	sd=sqrt((var1+var2-2.0*cov)/n);
+	t=(ave1-ave2)/sd;
+	prob=betai(0.5*df,0.5,df/(df+t*t));
+}